Who is your favorite tube seller?

Brent Jessee for NOS tubes https://www.audiotubes.com/

JJYaudio.com for Chinese tubes directly from China (Helen is legit) http://www.jjyaudio.com/index.asp

Apos for Ray Tubes (Excellent tubes) https://apos.audio/collections/apos-ray-vacuum-tubes

The problem with buying tubes is you really don't know how good they are unless you have a tube tester. Most people don't own one. Also, it really depends on what the type of tube you need (some have a reputation!) and how close the equipment requires that the tubes be matched. 

The consensus opinions offered above are generally pretty reliable.  I've bought tubes from everyone mentioned. I'd add TC Tubes to the list.

I have a good tube tester and have been able to verify tubes sold by Brent Jesse, Tube Depot and Jim McShane.

The big problem for me is I haven't yet built a rig to test for noise as this is important for tube phono stages. So, the only thing I can do right now is use the phono stages to test for noise. The above three vendors will sort for noise if you ask them and I've had good results.

When I purchased from Viva Tubes, I saw they had no optional noise testing. So, when I placed the order I asked them to sort for noise. The tubes I received were unacceptable for noise. They ignored my emails asking for a refund. That's why I don't recommend them.

Surprised to read so many recommending United.  Last time I checked they were vague about what one is actually buying.

I have bought most of my Mullards over the last few years from Brent Jesse.  Got some good ones from Tube Depot when Jesse was out of what I wanted.

Y'all take care,
Robert